I think there is a truth from Brain's post that is particularly important to grasp and that is that for most people, "things are just much simpler."
For many intellectually gifted individuals, there is a tendency to over-think things: Thing have to be rationalized, there has to be a foundation for their beliefs/actions, they themselves need to have full conception (or at least some contrived reasoning) for why they do things. It is simply part of the way they are. Intellectually gifted or no, I know this because I myself am this way-- I need to have a personal philosophy/reasoning behind everything.
That said, and I have come to understand this with time-- not everyone is that way.
Not everyone has that "need" for a greater reasoning, understanding, or cause. In fact, many people simply lack the intellectual capacity to have or care for a greater reasoning, understanding, or cause. They have desires, they act on them. They have a natural (or parent/upbringing programmed) sense of right or wrong, they act on it. Most such people can treat each other well, and live moral, honest and humble lives without any need for any greater voice of reason, religion or philosophy.
It's those "smart" individuals who have that constant synapse-fire of "why?" "what if?" with a high creed and tendency to tell people "go educate yourself!" who feel the constant necessity to have some greater reason behind their actions. These individuals often mistakenly believe this need is held by those around them as well.
Philosophically, I believe a code of ethics must exist as a black and white truth, and in terms from Kant, must be the same for all men everywhere and always. That's philosophy-- not how the real world tends to tick. Besides, it's not like there's any real way to define what "is ethical" in absolute terms, with or without the scriptures.
Also, on the actual subject of the thread, if you don't believe that at some point religious creeds have to be bent to, and submit to, the practical needs of the larger society, you are deluding yourself.
Just because religious tolerance is needed, and some allowances should be made, does not mean that society should bend over backwards just because of a certain group's "faith." There is a limit to everything, and in the end, practicality and efficiency will trump all other factors. In fact, historically and fundamentally, Religion only thrives when it is practical and it does make better lives and societies for those who practice it.
"Hmmm... a name for this plan..."